The nation's airlines struggled to stay on schedule in April, with nearly one in four flights arriving late, according to new government figures.
The airlines blamed furloughs of federal air traffic controllers and bad weather. A nationwide computer outage at American Airlines added to the slowdown.
The Transportation Department said Thursday that among the 16 airlines that report such information, only 77.3 percent of flights arrived on time in April. That was down sharply from 86.3 percent in the same month last year and below the April average of 80.26 percent for the previous 18 years.
Nearly 2 percent of all domestic flights were canceled in April, almost double the rate from the previous April.
Asked for an explanation, Jean Medina, a spokeswoman for trade group Airlines for America replied, "Short answer? Government-imposed air traffic controller furloughs."
In mid-April the Federal Aviation Administration began ordering about 10 percent of its controllers to stay home each day to help the agency meet automatic spending cuts. With fewer controllers to watch busy airspace, such as around New York and Washington, traffic slowed. After five days of complaints by airlines and passengers, Congress rushed through a bill to end the furloughs.
The airlines told the Transportation Department that 34.3 percent of April's delays were caused by bad weather, up from 28.5 percent in April 2012. They said that only 5.3 percent of delays were due to factors within their control, such as maintenance problems or crew shortages, although that was a slight increase over April 2012.
Hawaiian Airlines, Alaska Airlines and Delta Air Lines had the best on-time marks, with each over 85 percent, the government said.
The worst performance was turned in by American Eagle, with just 67 percent of flights arriving on time. Eagle is the regional airline of AMR Corp., whose American Airlines subsidiary had the poorest rating among the nation's five biggest carriers.
A computer system crash on April 16 caused American and Eagle to cancel more than 1,000 flights and hundreds of others were late. AMR CEO Tom Horton went on YouTube to apologize and blame the breakdown on a software problem that hit the company's main and backup computer systems.
Among the busiest 29 U.S. airports, passengers were most likely to be delayed on their way to Newark, N.J. — only 65.6 percent of flights arrived on time. At Salt Lake City, however, 85.3 percent of flights arrived within 14 minutes of schedule, which is the government's definition of on time.
Two flights were delayed on the tarmac for at least three hours, which could expose the carriers to fines from the Transportation Department.
One was an April 19 Delta flight that sat on the ground at New York's LaGuardia Airport for 183 minutes before returning to the gate. The other was an April 8 United Airlines flight from Pittsburgh to Denver that was diverted to Colorado Springs, Colo., where it sat for 182 minutes.
The rate of damaged, lost or delayed luggage rose slightly, to just over three bags for every 1,000 passengers.
The Transportation Department said that it received 684 complaints about U.S. airlines from consumers, seven fewer than in April 2012.